Drafting board construction



Feb. 15, 1966 .1. E. HALBERG 3,234,650

DRAFTING BOARD CONSTRUCTION Filed Sept. 19, 1962 2 Sheets-511%?I 2 .imlil il? K jm di lef@ 7 fw 7 3,234,650 DRAFTING BOARD CONSTRUCTION John E. Halberg, Two Rivers, Wis., assigner to Hamilton Manufacturing Company, Two Rivers, Wis., a corporation of Wisconsin Filed Sept. 19, 1962, Ser. No. 224,642 9 Claims. (Cl. 33-1) This invention relates generally to drafting boards and, more particularly, to an improved lightweight drafting board that will not warp due to atmospheric conditions.

Drafting boards now in general use usually include a plurality of strips of wood that are joined together to form a solid rectangular planar board. A sheet of linoleum is frequently attached to one side of the board, which acts as a working surface, and a pencil trough or molding is usually attached to the lower edge of the board to hold and prevent pencils and other items from falling to the floor.

This type of board has been deficient in that it is susceptible to warpage due to atmospheric conditions. Further, lboth wooden and linoleum working surfaces are relatively easily damaged by objects dropped on them and by the sharp points on drafting instruments.

Accordingly, it is a prirriary object of this invention to provide an improved drafting board that is not subject to warpage due to atmospheric conditions.

It is another object to provide an improved lightweight drafting board.

Still another object is to provide an improved drafting board having a working surface that is not easily damaged by either dropped objects or sharp points on drafting instruments.

A still further object is to provide a drafting board having an improved pencil trough and a reversible detachable molding therefor.

Other objects and advantages of the invention will become apparent from the following description taken in conjunction with the accompanying figures of the drawings, in which:

FIG. 1 is a top plan view, with some parts broken away to show underlying parts, of a drafting board embodying the features of the invention;

FIG. 2 is an enlarged sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary enlarged sectional view taken along the line 3-3 of FIG, 1;

FIG. 4 is an elevational view of a back cleat of the drafting board;

FIG. 5 is an enlarged elevational view of an end cleat of the drafting board;

FIG. 6 is an enlarged and elevational view of a pencil trough of the drafting board; and

FIG. 7 is an end elevational view of a molding for the pencil trough shown in FIG. 6.

In general, a drafting board embodying the invention comprises a plurality of boards joined together to form a rectangular planar frame having a hollow center. A cellular material or core is positioned in the hollow center of the frame and a secondary sheet of relatively stiff material is placed on each side of the frame and cellular material. A vapor barrier backing sheet is positioned over the secondary sheet on the underside of the board and a vapor barrier working sheet is positioned over the secondary sheet on the top side of the board. Two end cleats and a back cleat are secured to the two end and back edges, respectively, of the board, the cleats overlying the edges of both the working sheet and the backing sheet. At the front edge -of the board, a pencil trough is attached which also overlies the working sheet and the backing sheet.

The pencil trough is provided with a surface that may be used as a track for a drafting machine if one is used. Also provided is a molding for the pencil trough, which is reversible between two positions. In one position of the molding it permits the trough to be used as a track for a drafting machine, and in the other position the molding prevents pencils from falling to the floor when the board is tilted.

In greater detail, the drafting board has a body comprising four strips 10, 11, 12 and '13, FIGS. 1 to 3, joined together to form a substantially planar rectangular frame. A center strip 14 may al-so be provided, extending between the strips 10 and 12 parallel to the strips 11 and 13.V In the case of relatively small size drafting boards this center strip 14 may be omitted. The strips 10 to 14 are preferably of a wooden material such as basswood, and are preferably joined together by either staples 15, a suitable bonding material, or both.

The openings between the strips 10 to 14 of the frame are filled with two sheets 16 of a cellular material. In the event the center strip 14 is omitted, a single sheet of cellular material may be used. One suitable type of cellular material is expanded Honeycomb as manufactured by Union Bag-Camp Paper Corporation, which is a kraft paper structure fabricated to form nested hexagonal cells. The sheets are preferably pre-impregnated with a phenolic resin. As a specific example, a sheet of cellular material may lbe used wherein the base material weighs 99 pounds per ream or 3,000 sq. ft. of sheet stock, and the resin content is 11% of the finished weight. The cell size may be approximately :V4 inch as measured between the flat sides of the hexagonal cells when the sheet is fully expanded. This cellular material has the advantages of low weight, heat insulation, resistance to decay fungi, and dimensional stability because it is not affected by temperature changes. Further, this type of material has high compressive strength in a direction perpendicular to the plane of the sheets, but, nevertheless, the sheets cannot produce forces tending to warp the other members of the board.

A secondary sheet 18, FIGS. 2 and 3, is positioned on each side of the frame over the strips 10 to 14 and the sheets 16, the edges of each sheet 13 being flush with the outside edges of the strips 1t) to 13. These two secondary sheets 1S are made of a relatively stiff material. A presse-d fiber board such as Bernedji board or Masonite is preferable. The thickness of the sheets 16 of cellular material is made slightly greater than the thickness of the strips lil to 14 so that the cellular sheets 16 are crushed slightly, as indicated at 17 in FIG. 3, and held in place 'when the secondary sheets 18 are pressed firmly against the strips 10 to 14.

On the underside of the board covering the secondary sheet 18 is positioned a backing sheet 19 made of a vapor barrier material such as 50/65/50 gray-green wet strength one side duplex asphalt laminated Vapor barrier. On the top side of the board over the secondary sheet 18 is positioned a working sheet 20 made of a vapor barrier material such as vinyl-latex paper laminate. The inner surfaces of the secondary sheets 18 are preferably bonded to the strips 10 to 14 and to the cellular sheets 16 and 17, and the outer surfaces of the secondary sheets 18 are preferably bonded to the backing and working sheets 19 and 2) by applying a suitable adhesive and placing these members in a conventional hot press. Slots 21, which may be sawcuts, are formed in the two strips 11 and 13 for the purpose of Ventilating the interior of the board during the hot press operation.

Along the side edges, indicated generally by the numeral 22, of the frame, both secondary sheets 18 are provided with rabbets or reductions 23, FIG. 3. The backing sheet 19 and the working sheet 20 are folded into these rabbets 23, and U-shaped end cleats of met-al, FIGS. 3 and 5, are positioned with their arms over the working and backing sheets and their center portions covering the exposed edges of the strips 11 and 13. A series of elongated slots 26 are for-med in the lower arm of each of the end cleats 25 through which screws 27 are inserted and threaded into the strips 11 4and 13, as shown in FIG, 3.

As shown in FIG. 2, the secondary sheet 1S at the underside of the frame is also provided 'with rabbets 23 along both the back and front edges, indicated generally by the numerals 29 and 30, respectively. The backing sheet 19 is folded into these two rabbets 2S. The secondary sheet 18 at the top side `of the frame is also provided with rabbets 32 along both the back and front edges 29 and 30 and the working sheet 2t? is folded into the rabbets 32. The rabbets 32 are made narrower than the rabbets 2.3. A back cleat 33, FIGS. 2 and 4, is positioned over the back edge 29 of the frame, the cleat 33 being substantially Ushaped with one arm 34 substantially shorter than the other arm 35. The long arm of the back cleat 33 has a series of'holes 36 formed in it as shown in FIG, 4, and the center portion of the cleat 33 has holes 37 formed in it near its ends. The back cleat 33 is positioned with its shorter arm 34 over the working sheet 2t) in the rabbet 32 and the longer arm 35 over the backing sheet 19 in the rabbet 28. Screws 38 inserted through the holes 36 fasten the back cleat 33 to the strip l2. The holes 37 in the back cleat 33 may be used when mounting a drafting machine `on the board or they `may be used as additional support for the back cleat 33. Each end `of the back cleat 33 is provided with a longitudinally extending tongue 39 which extends between the arms of the U-shaped end cleats 25. The back cleat 33 is constructed with a relatively short arm at the top side of the board to increase the available working surface. Both arms of each end cleat 25 are made relatively long to provide greater rigidity for a T-square.

The front edge 3) of the board may be equipped with either a cleat identical with the back cleat 33 or a cleat in the form of a pencil trough 40, FIGS. 1, 2 and 6. This pencil trough 40 has a back wall 41, from which upper and lower flanges 42 and 43, respectively, project.

With the back wall 41 positioned against the botto-m edge 30 of the board, the upper llange 42 overlies the working sheet 20 in the rabbet 32 and the lower flange 43 overlies the backing sheet in the rabbet 28. Countersunk holes 44 and 45 are formed in the back wall 41 and the bottom flange 43, respectively, the holes 44 and 45 being offset longitudinally of the trough relative to each other, and the trough 4G is secured to the strip l@ by screws 46 inserted through the holes 44 and 45. A portion, indicated generally by the numeral 47 of the back wall 41 -of the trough 40 is preferably hollowed out for convenience of manufacture. Y

The pencil trough 4t) also has a bottom wall 48 that is below the plane of the working sheet 24B, and a front wall 49 that extends upwardly to approximately the plane of the working sheet 20. The upper end 50 of the front wall 49 is broadened and its upper surface 51 is approximately in the plane of the working sheet 29. A slot or bead opening 52 is formed on the outside of the front wall 49 below the upper surface 51.

As shown in FIG. 6, a molding 53 having a bead 54 may be attached to the pencil trough 40 by positioning the bead 54 in the bead yopening 52. This molding 53, FIG. 7, has two arms 55 and 56 which are substantially perpendicular to the bead 54, the arm 55 being substantially shorter than the arm 56 and the arm 56 being curved at its outer end. The bead 54 is symmetrical so that it may be inserted into the bead lopening 52 in the trough 4t) with either the short arm 55 extending upwardly as shown by the full lines in FIG. 6 or with the long arm 56 extending upwardly as shown by the dashed lines in FIG. 6. When the short arm 55 extends up the surface 51 of the trough 40 may be used 4.- as a track for a conventional drafting machine, and when the long arm 55 extends up, it prevents pencils and the like from rolling off the board and falling on the floor when the board is tilted.

From the foregoing description, it is apparent that a novel and useful drafting board has been provided. The board cannot warp due to atmospheric conditions because the strips 10 to 14 are enclosed by vapor barrier material and the sheets 16 of cellular material cannot cause warpage. The cleats on the edges of the board provide vapor protection and, in addition, hold the backing and working sheets 19 and 2t), respectively, in place. The end cleats 25 also provide a good rigid seat for the head of a T- square. The pencil trough also overlies both the backing and working sheets 19 and 20 and acts as a vapor barrier. The use of a working surface made of a material such as vinyl-latex paper laminate is advantageous because it is not easily permanently damaged by falling objects and the sharp points on drafting instruments. This type of material tends to flow back into irregularities in the working surface and, therefore, recovers rapidly. Tape rather than thumb tacks is usually used to hold a drawing in place on the board, so there is little danger of large holes being made in the working surface. The pencil trough may be used to hold pencils, erasers, etc. and it may also be used as a track for a drafting machine. The molding described is advantageous because it may be attached to the trough whether or not a drafting machine is being used.

I claim:

1. A drafting board comprising a planar substantially non-compressible body, a vapor barrier working sheet secured to and covering the top side of said body, a vapor barrier backing sheet secured to and covering the under side of said body, and a plurality of vapor barrier cleats secured to the edges of said body, each of said cleats including flanges which extend over portions of said top side and said bottom side of said body and overlie the edges of said working sheet and said backing sheet, whereby said body is enclosed by vapor barrier material and is not subject to warpage due to atmospheric conditions.

2. A drafting board comprising a planar substantially non-compressible body, a vapor barrier working sheet secured to and covering the top side of said body, a vapor barrier backing sheet secured to and covering the under side of said body, and a plurality of vapor barrier cleats attached to the edges of said body and overlying said working sheet and said backing sheet, one of said cleats forming a pencil trough.

3. A drafting board comprising a planar substantially non-compressible body, a vapor barrier Working sheet secured to and covering the top side of said body, a vapor barrier backing sheet secured to and covering the under side of said body, a plurality of vapor barrier cleats attached to the edges of said body and overlying said working sheet and said backing sheet, one of said cleats forming a pencil trough, said cleat forming said pencil trough comprising a back wall that abuts an edge of said body and has a flange overlying said working sheet, a bottom wall that extends below the plane of said working surface and has an extension overlying said backing sheet, and a front Wall that extends upwardly to approximately the plane of said working surface, the upper end of said front wall being broadened and ilattened to serve as a track for a drafting machine, a bead opening formed on the outside of said front wall, and a reversible molding having a bead adapted to be inserted into said bead opening of said trough.

4. A drafting board as in claim 3, wherein said molding has two arms extending perpendicular to said bead, one of said arms being longer than the other of said arms, and said bead being symmetrical so that said bead may be positioned in said bead opening with either said longer arm or said shorter arm extending upwardly, whereby when said molding is positioned with said longer arm extending upwardly said longer arm prevents pencils from falling to the floor, and when said molding is positioned with said shorter arm extending upwardly said trough may be used as a track for a drafting machine.

5. A drafting board having a pencil trough secured to the front edge thereof, said pencil trough having a front wall extending upwardly to substantially the level of the top surface of the board, the upper edge of said front wall providing a track for a drafting machine, said front wall having a forwardly opening longitudinally extending slot, and a molding having a bead adapted to be positioned in said slot, and a pair of arms of different lengths extending in opposite directions from said bead, said bead being symmetrical so that it may be selectively positioned in said slot with said arms respectively extending upwardly, whereby with the longer arm extending upwardly said longer arm extends above the trough to prevent articles from falling from the drafting board and with the shorter arm extending upwardly the upper edge of the front wall is available as a track for a drafting machine.

6. A drafting board comprising a planar generally rectangular, substantially non-compressible body, the top side and the bottom side of said body having rabbets formed therein at the four edges of said body, a vapor barrier working sheet secured to and covering the top side of said body, a vapor barrier backing sheet secured to and covering the bottom side of said body, said working and backing sheets being folded into said rabbets, and a plurality of vapor barrier cleats secured to the edges of said body, each of said cleats having ilanges which extend into said rabbets and overlie said working and backing sheets.

7. A drafting board as in claim 6, wherein the top surfaces of the flanges which overlie said working sheet are substantially flush with the top surface of the portion of said working sheet which is between said rabbets.

8. A drafting board comprising a planar substantially non-compressible body, a vapor barrier working sheet secured to and covering the top side of said body, a vapor barrier backing sheet secured to and covering the underside of said body, and a plurality of vapor barrier cleats secured to the edges of said body, each of said cleats including flanges which extend in the plane of said body and lie at against said working sheet and said backing sheet at the outer end portions thereof, whereby said body is enclosed by vapor barrier material and is not subject to warpage due to atmospheric conditions.

9. A drafting board as in claim 8, wherein said body includes a sheet of cellular material.

References Cited by the Examiner UNITED STATES PATENTS 794,359 7/1905 King 45-131 2,833,004 5/1958 Johnson et al 20-91 2,849,758 9/1958 Plumley et al 20-91 X 2,861,386 1l/1958 Paulsen et al. 45-131 2,893,076 7/1959 Herts 20-91 3,003,243 10/ 1961 Kanzelberger 45--131 X ISAAC LISANN, Primary Examiner.

T. B. SHERRY, Examiner. 

1. A DRAFTING BOARD COMPRISING A PLANAR SUBSTANTIALLY NON-COMPRESSIBLE BODY, A VAPOR BARRIER WORKING SHEET SECURED TO AND COVERING THE TOP SIDE OF SAID SIDE BODY, A VAPOR BARRIER BACKING SHEET SECURED TO AND COVERING THE UNDER SIDE OF SAID BODY, AND A PLURALITY OF VAPOR BARRIER CLEATS SECURED TO THE EDGES OF SAID BODY, EACH OF SAID CLEATS INCLUDING FLANGES WHICH EXTENDS OVER PORTIONS OF SAID TOP SIDE AND SAID BOTTOM SIDE OF SAID BODY AND OVERLIE THE EDES OF SAID WORKING SHEET AND SAID BACKING SHEET, WHEREBY SAID BODY IS ENCLOSED BY VAPOR BARRIER MATERIAL AND IS NOT SUBJECT TO WRAPAGE DUE TO ATMOSPHERIC CONDITIONS. 